In our cool season grasses, most root initiation and growth occurs in the spring with a smaller peak of growth during the cool weather of fall. For a comparison of root and shoot growth patterns see Figure 3.4 in the previous section and Figure 3.7 below. Maximum root growth and shoot growth do not occur at the same time. In fact, they may be considered somewhat antagonistic to each other.

Figure 3.7

Notice that root growth begins and peaks in activity before peak shoot growth activity in the spring. While there is some shoot growth activity during the summer months, providing that the grass plant is not in summer dormancy, root growth is very slow and depth of rooting is shallower. Finally, there is another peak period of root growth lagging slightly behind the late summer shoot growth period. Adjusting turfgrass management practices to optimize growth of either roots or shoots is a significant factor in establishing and maintaining a healthy lawn.

During hot, dry weather turfgrasses may enter a period of summer dormancy (Fig. 3.8). Dormant turfgrasses recover rapidly upon receipt of good soaking rains accompanied by cooling of the soil and air (Fig. 3.9).

A more detailed discussion on managing lawns during summertime hot and dry periods as well as summer dormancy is discussed in greater detail in Chapter 9 - Watering Practices.

Figure 3.8 Lawn area during summer dormancy.

Figure 3.9 The same lawn recovered from summer dormancy after receiving significant rainfall.